The present invention pertains to null steering apparatus in a communications system and apparatus for providing an improved reference signal for spread spectrum signals and the like. A copending application entitled "Null Steering Apparatus for a Multiple Antenna Array", Ser. No. 744,008, now U.S. Pat. No. 4,079,379, filed Nov. 22, 1976 by the same inventor and assigned to the same assignee, discloses apparatus for producing a reference signal for use in null steering apparatus when the desired signal is a carrier modulated by PSK data. A second copending application entitled "Null Steering Apparatus for a Multiple Antenna Array on an FM Receiver", Ser. No. 744,009, now U.S. Pat. No. 4,079,380, filed Nov. 22, 1976 by the same inventor and a coinventor and assigned to the same assignee, discloses apparatus for providing a reference signal in conjunction with an FM carrier wherein the data is periodically blanked for a very short period of time and the carrier is modulated only by a pseudorandom noise code during that period of time. In the receiver the PN code is removed from the carrier and the carrier is utilized as a reference only during the time that the data is blanked.
The present invention is an improvement over both of the inventions described in the copending applications in that none of the data is lost and a more accurate reference signal is produced.